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The Cryosphere Takes its name from the Greek word 'kruos' for frost. It is the portion of the climate system consisting of the world's ice masses and snow deposits including snow, solid precipitation, permafrost and seasonally frozen ground, ice sheets, ice caps and glaciers, sea-, river-, and lake ice.

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Where? Large areas of the cryosphere exist at temperatures close to melting and, as a result, are very sensitive to changes in temperature. This is a significant fact since much of the global cryosphere is located in high latitudes where enhanced warming is projected by climate models. Antarctica, Arctic, China, South America, North America

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Why Research? The relationship between the climate and the cryosphere is complex with numerous links and feedback mechanisms that change the sensitivity to climate response. Important linkages and feedbacks operating through its influence on energy, moisture and gas fluxes.

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Continental Ice sheets and Glaciers Continental ice is formed from snow accumulating at the surface and compressing over time into ice under the weight of the snow on the surface. Snow accumulates at the top during the winter and begins to compress under the weight of new snow. When the snow melts, the water percolates into the snow, filling available air spaces and freezing at the snow-ice boundary.

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Sea ice Sea ice includes frozen sea water, such as that in the Arctic Ocean and the oceans surrounding Antarctica, and frozen lake and river water, which occur mainly in the polar regions. Sea ice is formed by the direct freezing of the water on which it floats. If the water is salty, as it is in the ocean and in seas, during the freezing process the salt is left in the water, making the water more salty and denser and the sea ice less salty. Lake and river ice is frozen from fresh water generally and is therefore, not salty.

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Sea ice contd Sea ice regulates exchanges of heat, moisture and salinity in the polar oceans. It insulates the relatively warm ocean water from the cold polar atmosphere except where cracks, or leads, in the ice allow exchange of heat and water vapor from ocean to atmosphere in winter. The number of leads determines where and how much heat and water are lost to the atmosphere, which may affect local cloud cover and precip.

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Icebergs Icebergs are not considered sea ice. They are composed of ice originating from glaciers. Most of the icebergs infesting North Atlantic shipping lanes originate from Greenland glaciers.

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Sea Ice Sea ice floats on the surface of bodies of water and ranges from 0 to about 10 m thick with average thicknesses of 3 m in the Arctic and 1.5m around Antarctica. Under the stress of wind and ocean currents, sea ice cracks and moves around. The cracks expose areas of relatively warm ocean water to the cold atmosphere during winter that sets up a large exchange of energy from the ocean to the atmosphere.

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Sea ice contd Sea ice has a large seasonal cycle and changes on time scales of a few weeks to a few months. However, the magnitude of the seasonal changes is very sensitive to changes in the climate conditions in the atmosphere and oceans, extending the time scales associated with sea ice from months to thousands of years (i.e. ice age time scales).

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Since the end of the Little Ice Age (about 1850), glaciers have been melting steadily in most parts the world. This loss in glacier mass has been greatest in small alpine- type glaciers Current research indicates that global warming may be playing a significant part in this meltdown, as the current rate of glacier shrinkage is broadly consistent with estimated anthropogenic greenhouse forcing. More recent studies in the mid 1990s indicate that the Columbia Icefield glaciers (e.g. Athabasca, Saskatchewan glaciers) have further thinned and retreated dramatically, and that an acceleration in the flow has occurred.

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Graph showing the retreat of the Athabasca and Saskatchewan glaciers since 1700

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How researched? One method is a floating ice station which is harsh and dangerous. The purpose of the drifting stations was to collect all possible meteorological data while on an ice floe. This involves installing, calibrating, and maintaining the instruments.